op {
  graph_op_name: "RefEnter"
  visibility: HIDDEN
  in_arg {
    name: "data"
    description: <<END
The tensor to be made available to the child frame.
END
  }
  out_arg {
    name: "output"
    description: <<END
The same tensor as `data`.
END
  }
  attr {
    name: "frame_name"
    description: <<END
The name of the child frame.
END
  }
  attr {
    name: "is_constant"
    description: <<END
If true, the output is constant within the child frame.
END
  }
  attr {
    name: "parallel_iterations"
    description: <<END
The number of iterations allowed to run in parallel.
END
  }
  summary: "Creates or finds a child frame, and makes `data` available to the child frame."
  description: <<END
The unique `frame_name` is used by the `Executor` to identify frames. If
`is_constant` is true, `output` is a constant in the child frame; otherwise
it may be changed in the child frame. At most `parallel_iterations` iterations
are run in parallel in the child frame.
END
}
